But while Carson appears to be surging, one statistic suggests that Trump’s support actually may be more durable.

As The New York Times reported, 80% of Carson’s current supporters in Tuesday’s poll said it is too early to firmly commit to voting for the retired neurosurgeon. The number of voters who said that they would commit firmly to Trump, on the other hand, is 55%.

If more of Trump’s supporters are committed to backing him in the long haul, they’re unlikely to be swayed by poor debate performances, controversies, or other scrutiny that comes with being a top-tier candidate.

“I get these two polls — and remember, I don’t believe them, I don’t believe them — in Iowa. And I love Iowa,” Trump said at a campaign event on Saturday. He added on “Morning Joe” on Tuesday that he didn’t think recent polls were especially “scientific.”

Two polls last week gave Carson his first lead ever in Iowa. And Loras College and Monmouth University polls out Monday found Carson pulling into first place in the Hawkeye state — and leading by double digits.